Correct SPL use of EFI_UNICODE_COLLATION_PROTOCOL2

This converts 1 usage of this option to the non-SPL form, since there is
no SPL_EFI_UNICODE_COLLATION_PROTOCOL2 defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/efi_loader/efi_root_node.c b/lib/efi_loader/efi_root_node.c
index 21a014d..108c14b 100644
--- a/lib/efi_loader/efi_root_node.c
+++ b/lib/efi_loader/efi_root_node.c
@@ -68,7 +68,7 @@
 		 &efi_guid_dt_fixup_protocol,
 		 &efi_dt_fixup_prot,
 #endif
-#if CONFIG_IS_ENABLED(EFI_UNICODE_COLLATION_PROTOCOL2)
+#if IS_ENABLED(CONFIG_EFI_UNICODE_COLLATION_PROTOCOL2)
 		 &efi_guid_unicode_collation_protocol2,
 		 &efi_unicode_collation_protocol2,
 #endif